Radio Frequency Matrix Switches (RF Matrix Switches) are going to be required in order to provide High Availability (HA) internet protocol (IP) telephony over a cable television network. The RF Matrix Switches are physically and logically placed between a set of DOCSIS (Data Over Cable Service Interface Specification) Cable Modem Termination Systems (CMTS) and cable TV head-end network equipment. The cable TV network head-end equipment is typically an RF network of combiners and splitters that eventually exit the cable TV network head-end as an optical signal via a laser in the forward path; or enter into the head-end as an optical signal via Optical receiver from the return path. In the United States as an example, the forward path signals range from 54 MHz to 860 MHz while the return path signals range from 5 MHz to 42 MHz.
Cable television networks were originally designed to provide one-way, downstream transmission of electrical signals via Coaxial Distribution Plant (see FIG. 1 and FIG. 2) for distribution of Analog television signals. Modern Cable TV Networks are TWO-WAY (bi-directional signals) systems that are a combination of Coaxial Distribution plants and Fiber transmission and is commonly referred to as Hybrid Fiber Coax (HFC) Plant design (see FIG. 3). The intent of the HFC Cable TV Network design was to give CATV Networks Systems up to twice the bandwidth and significantly better Carrier to Noise Ratio (C/N), thus affording the Cable Operators to the ability to support the transmission of broadband data, telephony and digital video signals as well as the traditional Analog Video Signals. As is the case in both the older Cable TV Networks and the HFC Cable TV Networks, the Coaxial RF Distribution Plant portion of the CATV Network connects individual users (regardless of the type of application such as IP Telephony, Switched Telephony, data, digital video and analog video signals), to cable head-ends of various cable operator service providers. Standard size cables terminated by standard F-type connectors are commonly used throughout cable television networks. In CATV Headends, the standard connectors, typically threaded F type connectors, provide electrical and mechanical connections between coaxial cables and network components at numerous connection points within the Headend Facility.
Because the Cable TV Headend for HFC Networks has a high concentration of Return Path Nodes (See FIG. 3), there are multiple connection points required at various junctions in the Headend cable network. Often, dozens or hundreds of cables must be connected to a network component wherein space for connection points is limited. Connection points are therefore often crowded. The crowded interfaces leave minimal space for manual access or tool access to the threaded connection points. The access space constraints often cause installation and replacement of cables to be difficult and time consuming.
As stated above, the advent of bi-directional communication over cable networks for cable internet connections and cable telephony, significantly increases the number of cable connection points that are required at various network components because additional return path cables were added to cable networks. Furthermore, cable internet applications and cable telephony applications that require enhanced fault tolerance, i.e. high availability, require additional cable connections to accommodate more spare components. The additional number of connection points necessarily increases the size of network components to which cables are connected or increases crowding at the at the cable interface of the network components. Increased crowding at connection points reduces access to connection points for cable installation and replacement.
Visual access to cable connection points is also diminished at an overcrowded cable network interface. A technician's impeded view of a connection point may cause the technician to disconnect an incorrect cable or to connect a replacement cable to an incorrect connection point. Such errors are likely to decrease system availability.
High availability cable network systems involve a large number of connection points to an RF Matrix Switch. Conventional cables having F-type connectors are overly crowded at such matrix switch connection points thereby impeding visual and physical service access to the connection points. Standard F-Type connectors are mechanically secured to connection points by threaded collars, which require substantial access space for cable removal and installation. Installation or replacement of CMTS units in a High Availability cable network having conventional connections at crowded interface panels is therefore disadvantageously time consuming and susceptible to incorrect connections.
Interface panels are available having large areas to provide space for increasing numbers of connection points. The larger interface panels are disadvantageously wide or tall. Cable service providers and other users of such interface panels disfavor using interface panels having wider or taller dimensions because such panels consume valuable cabinet space and often do not fit properly into existing cabinets or mounting structures. For example, standard 6U interface panels having a vertical height of 10.5 inches do not meet customer marketing requirements for systems having superior space utilization.
Cable interface panels are typically oriented vertically so that cables protrude horizontally from connection points on the panel. Cables that protrude horizontally from connection points on a vertical panel typically hang from terminating connectors thereby pulling downwardly on the joint between the cable and its terminating connector. The downward stresses often degrade an electrical connection at the joint between the cable and its terminating connector.